Efficient Visible Light-Driven Photocatalytic Degradation of Pentachlorophenol with Bi2O3/TiO2-xBx

In this study, a new TiO2-based photocatalyst with both B doping and Bi2O3 coupling (Bi2O3/TiO2-xBx,) was synthesized to degrade pentachlorophenol under visible light (lambda > 420 nm) irradiation. The resulting Bi2O3/TiO2-xBx sample exhibited much higher photocatalytic performance than the counterparts with only B doping or Bi2O3 coupling or pure TiO2. This is because B doping could result in more visible light absorption to produce more photogenerated electron hole pairs, while Bi2O3 coupling could favor the separation and transfer of photoinduced charge carriers to inhibit their recombination. We interestingly found that the visible light-driven degradation of pentachlorophenol was mainly attributed to photogenerated holes and center dot O-2(-) other than center dot OH as reported previously because the hybridization of B 2p orbital and O 2p orbital could elevate the VB edge of Bi2O3/TiO2-xBx as compared to that of pure TiO2 and thus lower the oxidation ability of photogenerated holes, blocking the pathway of photogenerated holes induced oxidation of surface OH and water to generate center dot OH. The intermediates during the PCP photodegradation were systematically analyzed, ruling out the existence of high toxic polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. These results reveal that the visible light-driven photocatalytic degradation of PCP over Bi2O3/TiO2-xBx is an effective and green method to remove highly toxic halogenated aromatic compounds.